June 29 (Reuters) - NBC cut ties with real estate developer and TV personality Donald Trump and the "Miss USA" and "Miss Universe" pageants on Monday for making comments insulting Mexicans when he began his run for president earlier this month.

The pageants, part of a 50/50 joint venture with NBCUniversal for the English-language broadcasts that together have in the past year attracted 13 million viewers, would no longer air on NBC "due to the recent derogatory statements by Donald Trump regarding immigrants" the company said in a press release.

The decision by Comcast-owned NBC was announced four days after Spanish-language Univision said that it would not air the Miss USA pageant on July 12 and severed ties to the Miss Universe Organization. Trump's lawyer said the billionaire would sue.

Trump, in announcing on June 16 that he was seeking the Republican Party nomination for the November 2016 presidential election, described migrants from Mexico to the United States as drug-runners and rapists.

"They're bringing drugs, they're bringing crime, they're rapists, and some I assume are good people," he said in opening his campaign at Trump Tower on Manhattan's Fifth Avenue.

Public outrage and pressure followed, then the decisions by Univision and NBC, giving Trump a business headache. Trump needs to find another partner to help fund and broadcast the shows or he must pick up all the costs himself and find another media company willing to broadcast them.

Trump had already said he would not take part in "The Apprentice" reality TV show on NBC - in which he uses "You're Fired!" as his signature command to eliminate contestants - while he was running for the White House. NBC said sister show "Celebrity Apprentice" licensed from United Artists Media Group would continue.

The last season of Celebrity Apprentice averaged about 7.6 million viewers, according to Nielsen, which measures viewership.

Trump said on Monday that he stood by his comments.

"If NBC is so weak and so foolish to not understand the serious illegal immigration problem in the United States, coupled with the horrendous and unfair trade deals we are making with Mexico, then their contract violating closure of Miss Universe/Miss USA will be determined in court," Trump's statement said.

The Miss USA show that aired on a Sunday in June 2014 averaged about 5.6 million viewers, according to Nielsen. It said the Miss Universe show that aired on a Sunday in January 2015 averaged about 7.7 million viewers. By comparison, the series finale of popular TV period drama "Mad Men" drew 3.3 million.

In the aftermath of Trump's June 16 comments, Mexicans rich and poor, cabinet ministers and staunch critics of the government alike reacted angrily.

On Monday, when Trump spoke to a sold-out crowd of 350 people at the City Club in Chicago, a crowd of protesters, many of them Latinos, demonstrated outside, Chicago media reported. "Trump is a racist," they shouted.

Political analysts have said Trump, despite being one of America's most recognizable figures, is considered a long shot for the Republican Party nomination in the field of more than a dozen candidates. (Reporting by Anya George Tharakan in Bengaluru, Jennifer Saba in New York and Steve Holland in Washington; Writing by Grant McCool; Editing by Tom Brown)